106 DRY LAND FARMING 



moisture in dry areas will always be present in order to 

 guard against the contingency of crop failure. 



The functions of water in the soil. Chief among 

 the functions of water in the soil are the following: (1) 

 to improve its physical condition ; (2) to act upon it 

 chemically, and (3) to carry food to plants. Each of 

 these functions is greatly important. 



In the absence of water, soils cannot be tilled as a 

 rule without greatly increased labor. This explains why 

 breaking the soil in dry areas is usually more or less 

 laborious. Such unbroken soil is too lacking in moisture 

 during much of the year to plow easily. It is so firm that 

 heavy rains usually run away over the surface to a very 

 considerable extent. This explains why the wide-awake 

 farmer is so careful to push plowing rapidly at those 

 seasons when the ground has in it the largest amount of 

 moisture. The service rendered by water in facilitating 

 pulverization as the outcome of tillage is no less im- 

 portant. Deep plowing on stiff soils in the absence of 

 moisture is virtually prohibitory and pulverization is 

 even more difficult. 



All the ways in which water acts upon the soil 

 chemically cannot be discussed here, but it may be 

 said that it is a principal agent in promoting the decay 

 of vegetable matter in the soil, the acids from which aid 

 in the liberation of plant food. In the absence of mois- 

 ture buried vegetable substances in the soil will not de- 

 cay, and until the decaying process begins it cannot 

 act upon the soil chemically. Water also dissolves plant 

 food in the soil, changing it from the insoluble into the 

 soluble form, so that the plants may take it up readily. 

 Until such transformation takes place sufficiently, plants 

 may starve in the soil in the presence of an abundant 

 supply of unreduced food. In humid areas water is fre- 

 quently present in excess. When it is, two evils may 

 follow. One is the dissolving of plant food too rapidly 



